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Show HN: I spent 2 years building a personal finance simulator

projectionlab.com

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Re: Show HN: I spent 2 years building a personal finance simulator

#131

Post by scubakid »

brooodie wrote: post #129

Hey - this looks like a great project. Congratulations for getting to this point. I'm UK Based. I'm looking for a consumer facing replacement for ( https://www.timeline.co/ ) which is buggy and not really meant for non Financial Advisors. Kicking the tyres of this I'm running into an issue - not sure if this is a forum for bug reports/issues - if you'd prefer it elsewhere (discord?) I'm happy to do that. I've entered…

Thanks! And luckily I think I know what this is :)

Sounds like you may just need to pay a visit to the Expenses subsection of the House form within the plan interface (Real Assets section beneath the primary chart in the Plan tab).

If you've modeled those externally instead, then you can probably just zero-out the default assumptions for maintenance, insurance, property tax, etc.

Re: Show HN: I spent 2 years building a personal finance simulator

#132

Post by brooodie »

scubakid wrote: post #131
brooodie wrote: post #129

Hey - this looks like a great project. Congratulations for getting to this point. I'm UK Based. I'm looking for a consumer facing replacement for ( https://www.timeline.co/ ) which is buggy and not really meant for non Financial Advisors. Kicking the tyres of this I'm running into an issue - not sure if this is a forum for bug reports/issues - if you'd prefer it elsewhere (discord?) I'm happy to do that. I've entered…

Thanks! And luckily I think I know what this is :) Sounds like you may just need to pay a visit to the Expenses subsection of the House form within the plan interface (Real Assets section beneath the primary chart in the Plan tab). If you've modeled those externally instead, then you can probably just zero-out the default assumptions for maintenance, insurance, property tax, etc.

Thanks for the quick reply - I just found it myself (this comment helped: https://news.ycombinator.com/item?id=36853067)

Given it's come up twice maybe a UI tweak or prompt might be useful here but I'm loathed to give you any advice to you - this is superb work. Once I have more of a play I'll come back with any further thoughts.

Thanks again

Re: Show HN: I spent 2 years building a personal finance simulator

#133

Post by ripberge »

Very cool. Is there an easy way to easily toggle on/off various scenarios like "pay for private school for my children" to see how that affects wealth? I didn't see a way to do this without copying a whole plan.

My financial advisor does this with emaplan or blackmountain (or something) and I don't have access to this feature. It's very annoying and an incredibly important part of financial planning.

Re: Show HN: I spent 2 years building a personal finance simulator

#134

Post by aperrien »

scubakid wrote: post #3
gymbeaux wrote: post #2

I love that this has the ability to track multiple scenarios eg FIRE and LeanFIRE. I can see people using this to compare kids vs no kids as well. I would love the ability to simulate 401k contributions assuming an annual max contribution increase. For example, I will often put into an investment returns calculator that I am contributing $20k per year to retirement, however 10 years from now the annual max will proba…

PL assumes contribution limits increase over time to match inflation, so if you switch to visualizing results in actual currency (as opposed to today's currency), and you choose to contribute the max, you should see those nominal contributions increasing over time.

How can I alter the 401k match rate?

Re: Show HN: I spent 2 years building a personal finance simulator

#135

Post by j45 »

scubakid wrote: post #39
j45 wrote: post #32

This looks amazing, thanks for sharing it. I'm interested in a few angles that are leading me to look at your self-hosted option - is there any customizability that is possible? For example being in Canada, the basic features will work great, but some of the other types of accounts or programs will be different. It would be nice to be able to set it up in the software, and failing that, see if learning how the backen…

Most of the account and cash-flow priority types have customization options that can be used to do things like adjust liquidity/withdrawal rules and dial things in based on your circumstances. And if there are some specific areas where you'd like to see even more of that, just let me know.

Thanks for the reply, I'll check it out.

What stood out to me was

Roth, etc are very specific to the US.

Things like RRSP, TFSA, etc are more common in Canada. Maybe it's just configuring one of the flow types as you mentioned.

Re: Show HN: I spent 2 years building a personal finance simulator

#136

Post by mcho9257 »

scubakid wrote: post #34
mcho9257 wrote: post #21

Would love to see some integration of insurance and risk modeling (e.g. techniques to minimize downside risk, healthcare insurance, ACA subsidy interaction, P&C/home insurance, auto insurance risk) included as a feature — that's been incredibly hard for me personally in my own risk spreadsheets! DM me if you are interested in some of the actuarial data on some of these and how I model it...

Is there a certain kind of UI you envision for more first-class support for insurance modeling? Curious to hear your take on the best way to integrate that into the current setup.

Most unexpected insurance-covered events follow a Poisson-like distribution in both cost and frequency. By modeling different deductibles, premiums, and frequency of events, you can help plan and optimize for what insurance coverage you should purchase, how much drawdown you could expect to see in worst case scenarios, etc.

Re: Show HN: I spent 2 years building a personal finance simulator

#137

Post by orangepurple »

modeless wrote: post #126
orangepurple wrote: post #120

Earlier quoted context omitted.

I don't trust your random number generator. It takes some effort to get extreme speeds out of them.

The speed comes from running thousands of simulations in parallel on the GPU. The random number generator doesn't have to be any faster for this to be a huge speedup. It's possible to use any one you like. I did validate the one I'm using against various others and found equivalent results. I also have the simulation implemented on the CPU as well to validate the correctness of the results.

Are you suggesting you compared the result using Math.random() on CPU to the accelerated hash functions from https://www.shadertoy.com/view/XlGcRh (linked from your source code comments)?

Re: Show HN: I spent 2 years building a personal finance simulator

#138

Post by secabeen »

Very cool. Some of the assumptions really throw your plan out of whack, but digging around I eventually fixed it. An option to limit property tax increases would be nice, to reflect Prop 13 in California. The default estimate of 1.25% of my home value was blowing my entire projection out of the water given the 100+% increase we've seen in values over the last decade.

Also, a default tax rate of 30% is misleading, as that is the marginal rate for the next dollar, not the overall tax rate for someone in that bracket.

It does look good though, and a step up from the projecting that I can do in Quicken. I have 20 years of data in Quicken, which makes some things easy, but other things are hard.

Re: Show HN: I spent 2 years building a personal finance simulator

#139

Post by modeless »

orangepurple wrote: post #137
modeless wrote: post #126

Earlier quoted context omitted.

The speed comes from running thousands of simulations in parallel on the GPU. The random number generator doesn't have to be any faster for this to be a huge speedup. It's possible to use any one you like. I did validate the one I'm using against various others and found equivalent results. I also have the simulation implemented on the CPU as well to validate the correctness of the results.

Are you suggesting you compared the result using Math.random() on CPU to the accelerated hash functions from https://www.shadertoy.com/view/XlGcRh (linked from your source code comments)?

I believe that was one of the tests that I ran, yes. It was a long time ago. Obviously the results are not numerically identical when different RNGs are used but they converge as the number of iterations is increased. That said, I think you are right that the RNG could be improved, even if it doesn't affect the results right now.

Re: Show HN: I spent 2 years building a personal finance simulator

#140

Post by mirrorlake »

TheCaptain4815 wrote: post #36

"ProjectionLab has no link to your real financial accounts and the data you enter stays in your browser unless you choose otherwise. " I don't see why this would be a positive? I'd love an alternative to Personal Capital (since it got bought out), but without a direct connection to my banks/creditcards/etc, that connection just ends up being less secure.

This site helps you run financial simulations, though. It's not supposed to be a product you use to track your account balances.
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