**Limits on Constraints**

Using the basic Excel Solver, you can place** constraints on up to 100 cells** which are not decision variables. In addition, you can place** constant upper and/or lower bounds on the decision variables**, and you can place integer constraints on some or all of the decision variables.

If you have reached the limit of 100 constraints, consider these steps:

- Do you have constraint cells containing simple formulas like =A1 where A1 is a decision variable? Such cells count against the limit of 100; but if you apply the constraint directly to the decision variable cells (and use a constant right hand side), it won't.
- Do you have constraints involving (say) just two decision variables? If so, you might be able to place individual limits on the variables; this may change the range of possible solutions, but still allow you to make some progress.
- Do you have constraints where the right hand side is a cell or cells whose value depends on the decision variables? The Solver treats constraints like A1 <= A2 as if they were written A1-A2 <= 0, and counts them against the constraint limit -- even if A1 is a decision variable. Try to replace these constraints with individual cell limits if possible.
- Do you have constraints where the right hand side (RHS) is a formula, rather than a constant or a reference to cells which are constant? The Solver treats all RHS formulas as variable -- so A1 <= 2+2 would count against the constraint limit, even if A1 is a decision variable.

You may find that upgrading to Frontline's Analytic Solver products is a ** more efficient use of your time**. (Analytic Solver has all of our former Premium Solver capabilities, plus much more.) Analytic Solver Upgrade has a limit of 2,000 constraints for linear problems, and 500 constraints for nonlinear problems (apart from bounds on the variables and integer constraints) -- and it solves problems of this size in much less time. Our Large-Scale GRG Solver ** handles problems with thousands of constraints**, in addition to bounds on the variables.